1. Technical Field
The present invention relates to a liquid crystal display device, and more particularly, to a liquid crystal display device and a driving method thereof which are capable of preventing generation of a residual image upon power-off.
2. Description of the Related Art
Liquid crystal display (LCD) devices display an image using the electrical and optical properties of liquid crystals. This can be achieved by the anisotropic properties of liquid crystals exhibited in longer and shorter-axis directions of liquid crystal molecules in terms of physical values, such as refractive index and dielectric constant. One of the advantages of liquid crystals is that the molecular orientation and optical properties of liquid crystals can be easily controlled. In other words, LCD devices display an image by changing the orientation direction of liquid crystal molecules, and thus, controlling the light transmittance of the liquid crystals.
More specifically, such an LCD device displays an image by means of a liquid crystal panel in which a plurality of pixels are arranged in the form of a matrix. Each pixel of the liquid crystal panel displays a desired color through a combination of red, green, and blue sub-pixels, each of which controls the light transmittance thereof in accordance with a change in the liquid crystals. This change is made based on a data signal applied to the sub-pixel. To drive the liquid crystals, each sub-pixel is charged with a differential voltage between the data signal, which is supplied to a pixel electrode via a thin film transistor, and a common voltage, which is supplied to a common electrode. Since the liquid crystal panel of the LCD device is a non-luminous device, the LCD device is provided with a backlight unit for supplying light at the rear side of the liquid crystal panel.
However, such an LCD device has a disadvantage in that a residual image is displayed when the LCD device is powered off. This is not only because the liquid crystal panel is further driven for a predetermined time after the power supply unit of the LCD device is turned off due not only to a delay in cessation of the drive voltage supplied from the power supply unit to the driving circuit of the liquid crystal panel, but also due to the charged sub-pixels of the liquid crystal panel being slowly discharged through the associated turned-off thin film transistor.